How do winter citrus freeze and freeze?
In the process of planting citrus, the most fear is the winter frost damage. In the winter, we must do anti-freeze measures. Then, how do winter citrus freeze and freeze?
Prevention measures against citrus freeze damage
1. Choose cold-resistant varieties and cold-resistant rootstocks. Among the wide-skin citrus, Wenzhou mandarin orange, Zhuhong orange, citrus, local early, early orange, and orange are more resistant to cold. Pioneer orange, Jinjin, and navel orange in sweet orange have stronger cold resistance, summer orange and Xinhui orange. It is weaker. China's citrus rootstock resources are abundant, in addition to cockroaches, hybrids of Yichang orange, medlar and orange with strong cold resistance.
2. Choose good soil conditions and strengthen cultivation management
1 soil is the base of citrus, the depth of the soil layer, fat and thin, has a great influence on the cold resistance of citrus trees, deep roots and leaves, and enhanced cold resistance.
2 improve the soil and water conditions of citrus.
3 appropriate close planting, moderate results. Appropriate close planting can not only benefit early, but also reduce the freezing damage of citrus orchards. Our city belongs to the northern margin of citrus cultivation, promoting soil transplanting, planting and planting, dwarf and dense planting. This can lead to early results, can benefit before the onset of periodic frost damage, but also contribute to the increase in temperature in the citrus garden.
4 Control the autumn shoots in a timely manner to avoid freezing the late autumn shoots. At the same time, when the soil temperature has not decreased, apply enough base fertilizer to promote the restoration of the tree and enhance the cold resistance.
5 Carefully prevent pests and diseases that damage the leaves, branches and stems of citrus, so that the tree has enough nutrients (leaves and strong branches) to resist cold invasion.
3. Other various cold protection measures
1 Construct a windbreak and set up a wind barrier.
2 soil and bandage the trunk. Because the cold air sinks, the temperature in the neck of the citrus is often the lowest. In order to prevent the citrus plants, especially the roots and necks of the sap, from freezing, the soil and trunk are usually used to prevent freezing damage.
3 trunks painted white. Coating the white trunk with lime water has a certain effect on the prevention and cure of the main frost damage. For example, adding appropriate amount of yellow mud and fresh cow dung in lime water has better antifreeze effect.
4 foliar spray anti-steam insulation agent. The citrus canopy is sprayed with a steam-proof and heat-insulating agent to form a molecular film on the citrus leaf surface, thereby inhibiting water evaporation of the leaves and reducing frost damage.
5 smoked smoke cloud: before the cold wave forecast cools down or after the heavy snow, in the sunny weather without wind, the weeds and branches are piled up in the citrus garden, as the smoked smoke pile, burning in the evening, making it smoke, artificially making clouds, It can suppress the radiation backflow and prevent frost.
6 Pre-freezing and anti-freezing: Before the cold wave comes, the citrus garden is filled with water, which plays an important role in preventing freezing damage. Irrigation can increase the water content of the soil, and the evaporation of water can cause the temperature to not drop suddenly.
4. Treatment after citrus freezing. The speed of recovery of citrus trees after freezing depends on two factors: first, the severity of the degree of freezing damage, and second, whether the recovery measures taken after freezing are timely and appropriate.
1 In case of heavy snow embedded in the crown, the snow on the crown should be shaken in time to avoid breaking the branches. For the torn branches, the branches and leaves should be properly cut off to reduce consumption.
2 Ground irrigation, especially after dry freezing, roots and trees need more water, and should be timely flooded.
3 loose soil to increase temperature. Immediately after thawing, loosen the soil under the canopy to maintain geothermal heat and increase soil temperature. According to reports, 6 calories per square centimeter of surface can be released per hour. In winter, the soil temperature is higher than the temperature, and the loose soil can maintain the heat of the soil, which is beneficial to the citrus root system.
4 fertilization to restore recovery. After freezing, the function of the tree body is significantly weakened, and the fertilization should be carried out with water and fertilized.
5 trim and saw dry at the right time. Branches are not as easy to identify in the short term as they are after freezing. After the branches are frozen, the conduits are not blocked, and the fertilizer water absorbed by the roots can still be consumed along the conduits as capillary water and gaseous water. The shearing (saw) branches are premature, mis-scissing occurs, and the shearing (saw) is too late, so that the tree body wastes water. Therefore, it is necessary to cut (saw) the frozen branches in time. For larger wounds after shearing (saw), a protective agent should be applied to reduce evaporation of water. The protective agent can be selected from yellow mud slurry and fresh cow dung plus 100ppm2.4-D; Vaseline 250g plus carbendazim 5g; butter 100g plus tropoxin 2g.
6 dry coated white sunscreen. The frozen citrus trees, especially the branches and stems of the third and fourth grade freezes, are painted with white to prevent the sunburn and the branches from cracking.
7 control pests and diseases. Pay attention to the control of the mites that damage the leaves, in order to facilitate the growth of leaves and new shoots.
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